Odani Castle Ruins: Azai Clan Mountain Fort

Castle of the Azai Clan

Odani Castle is a grand mountain castle built on 495-meter Mount Odaniyama, prospering as the residence of the Azai clan for three generations during the Warring States period. Attacked by Oda Nobunaga in 1573, it fell and the lord Azai Nagamasa took his own life. His wife Oichi and their three daughters, the Three Azai Sisters, left the castle and were taken into the Oda camp. Renowned as a formidable mountain fortress, it is counted among Japan's five great mountain castles and is designated a National Historic Site.

The Three Azai Sisters

Nagamasa and Oichi's three daughters — Chacha (later Yodogimi, concubine of Toyotomi Hideyoshi), Hatsu (wife of Kyogoku Takatsugu), and Go (wife of Tokugawa Hidetada and mother of the third shogun Iemitsu) — survived the turbulent age, each fatefully bound to a figure of great power. Their story has been dramatized in NHK taiga dramas, drawing many fans to the ruins.

Mountain Castle Trekking

Trekking trails from the mountain base to the main enclosure remain well maintained, making this a thrilling destination for mountain-castle enthusiasts. The succession of terraced enclosures — Bansho, Ochaya, Ohiroma, Honmaru, Kyogoku-maru and Sanno-maru — along with stone walls and defensive cuttings scattered throughout, lets visitors imagine the fortress in its prime. From the summit, views open across Lake Biwa and the Anegawa battlefield.

Odani Castle Sengoku History Museum

The museum at the mountain base offers detailed history of Odani Castle and the Azai clan, with rich exhibits on the Three Azai Sisters. A visit before climbing makes the trek more rewarding. It opens 9:30 to 17:00 (last entry 16:30) and closes on Tuesdays.

Access & Basic Information

The nearest station is Kawake on the JR Hokuriku Line, from which the Ote trailhead is reached on foot or by taxi. From central Nagahama it is about 20 minutes by car, with convenient access from the Nagahama interchange on the Hokuriku Expressway. On many weekends in spring and autumn, an Odani Castle shuttle bus runs from the base to the mid-slope Bansho enclosure with a local storyteller guide, easing the climb for beginners. Operating periods vary by year, so check in advance.

Practical Travel Notes

• Best seasons: Fresh green in May and autumn colour in November are most comfortable for climbing. Beware heat and insects in summer and snow in winter.
• Time needed: About 2 to 3 hours round trip from the Ote trailhead to the main enclosure; extending to Sanno-maru or Ozuku peak makes a half-day outing. Bring sturdy shoes, water and rain gear.
• Avoiding crowds: Trailheads get busy on shuttle-bus mornings; weekdays are quieter for a peaceful walk.
• Nearby spots: Easily combined with Nagahama Castle Museum, the Kurokabe Square district, the Anegawa battlefield and Shizugatake in northern Omi.
• Budget: Museum admission is around 350 yen for adults; the climb itself is free.

A Word of Advice

Some footing is rough, so trekking shoes are preferable to ordinary sneakers. Carry a bear bell and keep hydrated. Stopping first at the museum makes the stone walls and enclosures far more meaningful.

📚 Sources

This article was edited with reference to information on the national historic site of the Odani Castle ruins, the Odani Castle Warring States History Museum at the foot of the mountain, and tourism guidance from Nagahama City. Explanations from the museum and the region were consulted for the history of the three generations of the Azai clan and the three Azai sisters and the site status as one of the five great mountain castles of Japan. Museum hours and closing days and the operating period of the Odani Castle shuttle bus may change, so please check official information before you set out.

Visitor Checklist

• Suggested route: Learning the history at the foot-of-mountain museum first, then tracing the enclosures from the guardhouse site up to the main bailey, Kyogoku bailey, and Sanno bailey, deepens your understanding.
• Estimated time: Allow about half a day for the trek from the base to the main bailey and sightseeing.
• What to wear: The mountain-castle trail is hilly, so comfortable shoes and easy-to-move clothing are essential.
• Museum: It opens roughly 9:30 to 17:00 (entry until 16:30), closed Tuesdays, and is a good stop before climbing.
• Shuttle bus: A guided shuttle bus runs in some periods, mainly on spring and autumn weekends, making the climb easier for beginners; check the operating period in advance.
• Best time of day: The summit overlooks Lake Biwa and the Anegawa battlefield, so a clear daytime visit is recommended.